Electromechanical brake pressure generator unit

Abstract

An electromechanical brake pressure generator unit (10) of a brake-by-wire brake system can only be activated electronically and comprises a master brake cylinder (20), an electric motor (14) and a multi-stage intermediate transmission (16). A spindle-nut unit (18) comprises a nut (40) having a centring surface (42) by way of which the piston (48) of the master brake cylinder (20) is centred.

The invention claimed is: 
     
       1. Electromechanical brake pressure generator unit of a brake-by-wire brake system, wherein the brake pressure generator unit ( 10 ) can only be activated electronically, having a master brake cylinder ( 20 ) for generating a hydraulic pressure for at least one hydraulic brake circuit, an electric motor ( 14 ), an intermediate transmission ( 16 ) driven by the electric motor ( 14 ), and a spindle-nut unit ( 18 ) having a spindle ( 30 ) which can be driven by the intermediate transmission ( 16 ) and a nut ( 40 ) which is mounted in a rotationally fixed manner and can be displaced axially by the spindle ( 30 ), wherein the nut ( 40 ) axially displaces a piston ( 48 ) which is displaceable in the master brake cylinder ( 20 ). 
     
     
       2. Brake pressure generator unit according to  claim 1 , wherein the spindle ( 30 ) has an axis of rotation and the electric motor ( 14 ) has a motor axis which lie parallel to one another, wherein the electric motor ( 14 ) is arranged at the side of the spindle ( 30 ). 
     
     
       3. Brake pressure generator unit according to  claim 1 , wherein the intermediate transmission ( 16 ) is a multi-stage gearwheel transmission. 
     
     
       4. Brake pressure generator unit according to  claim 1 , wherein the electric motor ( 14 ) is coupled with a control unit ( 12 ) which is seated adjacent to the electric motor ( 14 ) and at the side of the spindle ( 30 ) and/or the piston ( 48 ). 
     
     
       5. Brake pressure generator unit according to  claim 4 , wherein mounting of the nut ( 40 ) takes place by way of a rotation-blocking element ( 62 ) to which the nut ( 40 ) is fastened. 
     
     
       6. Brake pressure generator unit according to  claim 5 , wherein the rotation-blocking element ( 62 ) is displaceably mounted and centred on guide rods ( 66 ). 
     
     
       7. Brake pressure generator unit according to  claim 6 , wherein the guide rods ( 66 ) are holders for the master brake cylinder ( 20 ). 
     
     
       8. Brake pressure generator unit according to  claim 1 , wherein there is a centring part ( 46 ), in particular a centring sleeve, adjacent to the nut ( 40 ), which centring part is seated axially between the nut ( 40 ) and the piston ( 48 ) and centres the piston ( 48 ) relative to the nut ( 40 ). 
     
     
       9. Brake pressure generator unit according to  claim 8 , wherein the centring part ( 46 ) and the nut ( 40 ) are radially aligned relative to one another by way of a convex, in particular spherical-segment-shaped, centring surface ( 42 ) and a complementary concave centring surface ( 44 ) abutting thereon. 
     
     
       10. Brake pressure generator unit according to  claim 1 , wherein the spindle ( 30 ) is radially and axially mounted on a holding part ( 32 ) by way of a fixed bearing ( 36 ). 
     
     
       11. Vehicle brake system, wherein the vehicle brake system is a brake-by-wire brake system and is equipped with a brake pressure generator unit ( 10 ) according to  claim 1 .